1. Field of the Invention
The present invention relates generally to portable terminals including digital communication devices such as cellular phones, personal digital assistants (PDAs), hand held phones (HHPs), camera phones, game phones, and Internet phones, and in particular, to an antenna device for a portable terminal, of which transmission/reception sensitivity is adjusted according to sliding movement on the portable terminal.
2. Description of the Related Art
The term portable terminal commonly refers to an electronic device with which a user can perform wireless communications. The design trend of portable terminals is geared towards portability and thus miniaturization light-weight designs. Moreover, multimedia compatibility is also desirable. Portable terminals are thus evolving into small, light-weight multi-function communication terminals which can also be adapted to various multimedia or Internet environments. Also, as portable terminals have become more prevalent they have transformed from being luxuries to being necessities throughout the world.
Conventional portable terminals are classified into several types by appearance. For example, according to the appearances of portable terminals, the conventional portable terminals are classified into bar type, flip type, and folder type terminals. The term bar-type terminal typically refers to a terminal in which a single housing is configured in a bar type manner, the term flip type terminal typically refers to a terminal in which a flip is rotatably assembled with a bar type housing by a hinge apparatus, and the term folder-type terminal typically refers to terminals in which a folder is rotatably assembled with a single bar type housing using a hinge apparatus so that the folder can be folded over the housing.
Also, according to wearing positions or methods, the portable terminals may be classified into neck-wearable type and wrist type terminals. The neck-wearable type terminal typically refers to a portable terminal which a user can wear around the user's neck using a string, and the wrist type terminal typically refers to a portable terminal which a user can wear around the user's wrist.
Also, according to the methods used to open/close the portable terminals, the portable terminals can be classified into rotation type and sliding type terminals. The rotation type terminal means a terminal in which two housings are rotatably assembled and open/closed while facing each other, and the sliding type terminal means a terminal in which two housings are open/closed by sliding movement in a longitudinal direction. Those skilled in the art will easily understand the variously classified portable terminals described above.
Conventional portable terminals thus are developing into advanced portable terminals which are capable of enabling high-speed data communication and/or voice communication functions. That is, in order to meet the increasing customer's demands, future portable terminals will provide services using a wireless communication technology for transmitting data at a high data rate.
Recently, conventional portable terminals have begun to adopt (internally and/or externally located) cameras, thus popularizing the transmission of digital images (e.g., photographs, graphics, icons, etc.).
However, antenna devices adopted by the conventional portable terminals have the following disadvantages. In a case where the conventional portable terminal adopts a retractable antenna comprised of a helical antenna and a rod antenna as an antenna device, its user must inconveniently pull out the retracted rod antenna to increase reception sensitivity when the reception sensitivity decreases, and retract the pulled-out rod antenna after a call. When the portable terminal is carried in a pocket, its portability is decreased due to protrusion of the antenna device. Moreover, when a portable terminal with an external antenna drops, the external antenna is more likely to be damaged.
Furthermore, in a case where a portable terminal incorporating a fixed built-in type antenna device, when antenna's reception sensitivity decreases due to geographical features, there is no way to cope with the decrease in reception sensitivity.